Hydraulic valve mechanism



Nov. 28, 1933. s. E. A. HALLETT ET- AL 1,936,657

HYDRAULIC VALVE MECHNISM'4 Filed Aug. 5. 192'? Patented Nov. 28, 1933 HYDRAULIC VALVE MECHANISM George E. A. Hallett and Leroy W. Shutts, Detroit, Mich., assignors to General Motors Research Corporation, Detroit, Mich., a corporation of Delaware Application August 5, 1927. Serial No. 210,824

7 Claims.

This invention relates to hydraulic operatingA mechanism of the type in which a body of fluid is interposed between an operating and an operated part to transmit movement from the. one to the other. The object of the invention is to provide means for automatically venting air which may collect in the chamber and interfere with operation of the mechanism. Essentially, the invention consists in providing more or less continuously open vent, preferably at the highest point in the hydraulic chamber. In its simplest embodiment, the vent may be constituted by a Vfitting comprising a needle valve which is 'adjusted so as to be slightly spaced from its seat. Instead of having the vent permanently open, an intermittently.,- open vent may be provided. This may be accomplished by providing an extension-on one of the plungers working in the hydraulic chamber, the extension having a sliding t in an aperture or guide formed in a wall of the hydraulic chamber and being provided witha port uncovered during a portion of its stroke permitting the escape of air and oil from the chamber.v In some cases, the port may be dispensed with the extension simply being a sloppy iit in the guide so that air may escape around the plunger.4 With this construction,v the vent is, to some extent, cleared of obstructing matter by 'the motion of the reciprocating part.

The invention likewise embodies an improved design of hydraulic chamber which facilitates machining and enables the device to be produced at smaller cost.

In the drawing, Figure 1 is a vertical section thrua conventional automobile engine showing our improved valve operating mechanism applied thereto. Figures 2 and 3 are sectional vviews Ythru slightly diieren't forms of valve mechamsm.

Reference character 4 indicates a conventional automobile engine having piston 6, cam shaft 8, push rod 10 and valve 12, the Valve being held upon its seat by coil springs 14. 16 indicates a casting. secured to the top of the engine block, the casting being provided with a transverse cylindrical bore 18 forming the hydraulic chamber and with intersecting bores 20 and 22, bore 20 receiving plunger 24, and'bore 22 receiving vplunger 26. The plunger 24 is yieldingly held in engagement withu the` upper end of push. rod` 10 by meansof. spring 28. While this spring is' (Cl. 12S-90) under side of the casting 16. To the upper end of the'y plunger 24 is secured the extension'BO which has a loose sliding fit in aperture or guide 32 formed in the upper wall of the chamber 16.

Plunger 26 is yieldingly held in engagement with the spindle of the valve 12 by means of spring 33 shown as of the rat-trap type-that is, the spring consistsof a strip or Wire of spring metal bent to formarms 34 and 36 connected by afloop 65 38 of one or more turns.

40 indicates an oil reservoir whichmay extend along the cylinder block and serve for Ifilling any number `of hydraulimchambers 18, fas desired.

,Oil from` the reservoir 40 vis admitted to the I .chamber 18 thru check-valve 42 carried in plug I0 crankcasethru conduit 48. `indicates a pipe 75 for returning excess oil to the crankcase. A

pressure relief valve 52 may be provided inxthe return pipe.

With the described construction, it is apparent that the chamber 18 may be formed in the cast- 80 ing 16 by drilling the casting from the righthand end and the bores 20 and 22 may be similarly formed. This provides a cheap construction and, at the same time, makes it possible to have an hydraulic chamber with all its surfaces machined so as to prevent the trapping of air bubbles along the walls of the chamber.

In the operation of this form of device, upward motion of the push rod 10 transmitted thru lthe plunger 24 results in displacement of the 90 fluid in chamber' 18 and consequent forcing of the plunger 26 downwardly vunseating the valve 12. During this part of the cycle check valve 42 is forced into engagement with its seat preventing the return of oil to the reservoir but, owing to the loose ft of extension 30 in guide 32, air and oil will be forced out into receptacle 50 which may be in the form of a trough. The oil, overowing the trough, returns to the crankcase thru the push rod guides. x the cam moves from beneath the push rod, the oil in the chamber 18 is relieved of pressure and the plunger 20 follows up the push rod under'the inuence' of spring` 28.v As a consequenca'a partial vacuum is produced in the chamber 18 105 which results in drawing oil into the chamber 18 from the reservoir 40 past check valve 42. The oil in the chamber is thus constantly replenished and on each operating stroke', `the oil and con- `tained air collecting in the highest part of the When the high point of chamber is forcedout in the manner described. The fact that extension 30 Works in the guide 32 insures that the vent will, at all times, be clear -of foreign particles so that passage of air is not interefered with.

In the form shown at Figure 2, the construction of the hydraulic chamber is somewhat simplied and a xed vent is provided. Here 60 indicates the hydraulic chamber which, as above, is formed by drilling the casting 62 from the right-hand end. The outer end of the chamber is closed by plug 64 containing ball check valve 66. The valve controlled passage 68 provided in the plug and communicating with reservoir '70. The reservoir is supplied With oil from the crankcase thru conduit 72, preferably at a pressure of about 20 lbs. per. square inch. Conduit 74 equipped Withpressure relief valve '76 providesof oil and air from the chamber 60 into the' trough 80. In this form of the invention, the machining of the hydraulic chamber is further simplified and the air vent is free of moving parts.

Figure 3 Ishows somewhat diagrammatically a further modification. In this form, the bore 90 is closed by a simple plug 92, While the oil reservoir is located at the opposite end of the casting, as shown at 94. The reservoir 94 communicates with the hydraulic chamber 90 through port 95 which is uncovered on the downstroke of the piston 102. Oil is' supplied to this reservoir through conduit 96 while pressure relief valve 98 and conduit 100 permit the return of excess oil to the crankcase. Piston 102 is provided with tubular extension 104 working in guide 106 formed in the opposite Wall of the chamber 90. The extension 104 is hollow and is provided with an aperture 1 08 which during the major portion of the operating stroke of the plunger 102 lies within the guide 106 but, during the return stroke and the initial portion of the operating stroke is exposed within the chamber 90 so as to permit the escape of oil and air particles. The piston 102 may be rigidly secured to the valve tappet or may be separate and yieldingly held in engagement with the tappet by means of a coil spring such as shown at 28 in Figure 1. There is thus provided a simple form of mechanically operated vent for relieving the chamber of its air content. It is understood, of course, that the oil in the reservoir 94 will be maintained at suitable pressure, say 20 lbs., to insure that the chamber 90 is at all times full of oil.

We claim:

1. In hydraulic valve operating mechanism, the combination of an operating plunger, an operated plunger, a body of fluid interposed between said plungers, said operating plunger being provided with an extension guided in an aperture in the Wall of said chamber, said aperture and extension cooperating to permit the escape of air.

2. A head for hydraulic valve gear for internal combustion engines provided with a transverse vcylindrical socket forming an hydraulic charnber, means for closing one end of said socket, and angularly related bores intersecting said transverse bore for receiving the operatihg'and operated plungers.

3. In hydraulic valve operating mechanism, the combination of an hydraulic chamber, operating and operated members Working in the chamber, and a mechanically operated leak for permitting escape of air from the chamber, one of said members comprising a reciprocating plunger and said leak comprising an extension on said plunger guided in an aperture in the chamber Wall.

4. In the combination as defined in claim 3, said leak being arranged at the highest point in said chamber.

5. A head for hydraulic valve gear for internal combustion engines provided with a cylindrical socket forming an hydraulic chamber, means for closing one end of the socket, oisetv passages communicating with said socket, an operating member working in one of said passages, and an operated member working in another of said passages.

6. Hydraulic valve mechanism comprising an hydraulic chamber, operating and operated members working in the chamber, a supply chamber, and a tting provided with a passage establishing communication between the reservoir and chamber, said tting being accessible from outside said chambers and readily removable therefrom for replacement or repair.

7. The combination as dened in claim 6, and a valve carried by the tting for controlling flow through the passage.

GEORGE E. A. HALLETT. LEROY W. SHUTTS. 

